In the past, there have been many types of unicycles and bicycles for such purposes, but they all have been used for performing stunts (e.g. at the circus shows) or limited only to special use. Consequently, the prior unicycles could not have been used as usual sporting and playing apparatus like bicycles, and when children and unskilled adults ride on the prior unicycles, they must be always ready to risk accidents. Accordingly, the prior unicycles and the like are not suitable for the playing and sporting apparatus in view of the physical training and the entertainment purposes.